Method for recording digital signals on multiple-layered disks

ABSTRACT

A method of recording digital signals on a disk having at least a first recording surface and a second recording surface. The digital signals are in the form of a data frame including a lead-in block and n data blocks. The lead-in block has a same format as the n data blocks. The method includes the steps of assigning n block addresses to respective ones of the n data blocks, assigning, to each of the n data blocks, information identifying an area on the disk in which a respective one of the n data blocks is to be recorded, recording m data block (0&lt;m&lt;n) of the n data blocks on the first recording surface of the disk, recording remaining (n-m) data blocks of the n data blocks on the second recording surface of the disk, and recording the lead-in block at the head of the data frame. The lead-in block includes information identifying an area on the disk in which the lead-in block is to be recorded, a number of recording surfaces, the block address of one of the m data blocks recorded last on the first recording surface, and the block address of a last one of the n data blocks in the data frame.

CROSS-REFERENCES TO RELATED APPLICATIONS

This application is a continuation of application Ser. No. 09/084,931filed on May 28, 1998, now U.S. Pat. No. 6,076,135 which is a divisionof application Ser. No. 08/669,245 filed on Jun. 24, 1996, now U.S. Pat.No. 5,966,721.

BACKGROUND OF THE INVENTION

The present invention relates to a digital signal recording method and adisk reproducing apparatus, and more particularly to such a method andan apparatus for recording a digital signal in the form of a data blockon a disk adapted to be accessed by a host computer and for reproducingthe digital signal from the disk.

A CD-ROM (CD-Read Only Memory) is a conventional example of this type ofdisk on which digital signals are recorded in units of a data block.Like the techniques described in Nikkei Byte, September 1994, p. 146, inthe CD-ROM, data blocks composed of effective data and block addressesare recorded outward in order from the innermost track on the recordingsurface of the disk. When such a disk on which such data is recordedusing the above technique is accessed and reproduced in accordance witha command from the host computer, a starting block address and atransfer block count are designated along with the access command, anddesired data blocks are accessed and reproduced in accordance with suchcommand and data.

Recently, disks each composed of two subdisks stuck to each other whoserecording surfaces are readable from one side, disks having an upperrecording surface and a lower recording surface whose recording surfacesare readable from one side, and disks each composed of twostuck-together sets of upper and lower recording surfaces which arereadable from one side have been standardized. See, for example, thearticle "Confidence in Unique Standards of DVDs", Nikkei Sanqyo Shinbun,Feb. 24, 1995, and the article "Second Stage of Struggle for DVDStandards", Nihon Keizai Shinbun, Apr. 20, 1995.

When a digital signal is recorded using the above-mentioned technique onany of those disks having a plurality of recording surfaces, the hostcomputer only recognizes the disks as having independent recordingsurfaces. In order to enable all of the recording surfaces to beaccessed, the interface via which data is sent to and received from thehost computer is required to be changed, and hence the conventionalinterface cannot be used as it is.

The above-mentioned technique has the problem that each time a recordingsurface to be reproduced is changed, it is necessary to read theinnermost lead-in area before access and reproduction, such that ittakes a long time to resume access and reproduction.

SUMMARY OF THE INVENTION

It is therefore an object of the present invention to provide a digitalsignal recording method and a disk reproducing apparatus which arecapable of accessing at high speed all of the recording surfaces presentin the disk and reproducing a digital signal using the conventionalinterface as it is.

In order to solve the above problem, in the digital signal recordingmethod according to the present invention, a data frame is constructedwhich includes n (which is a natural number) data blocks recordable on afirst digital signal recording surface and a second digital signalrecording surface present on a disk and readable from one side of thedisk, each data block being composed of a synchronization (sync) signalindicative of the boundary between the two data blocks, a block addressindicative of the address of the data block on the recording medium, anddata.

Further provided at the head of the data frame is a lead-in block havingthe same format as the data blocks and including information indicatingthe range of block addresses recorded on each of the recording surfacesof the disk, information indicating the configuration of the data frame,and a flag identifying a method for reproducing the data frame. Thelead-in block and the data blocks of block addresses 1 to m (which is anatural number smaller than n) of the data frame are recorded on thefirst recording surface of the disk and the data blocks of blockaddresses (m+1) to n are recorded on the second recording surface of thedisk. The disk has a multilayered structure with the correspondingrecording surfaces. The first to m-th data blocks are arranged outwardfrom the innermost track on the first recording surface and the (m+1)thto n-th data blocks are arranged inward from the outermost track on thesecond recording surface so as to enable the data blocks to be tracedcontinuously.

The reproducing apparatus comprises means for processing a digitalsignal recorded on the disk in a predetermined format, means forsending/receiving commands and data to/from a host computer, means forcontrolling the whole apparatus in accordance with a command obtained bythe sending/receiving means, means for moving a signal pickup to adesired position on the disk, means for controlling the focus of thesignal pickup to access the recording surfaces selectively, means forcontrolling the rotational speed of a disk motor, means for detectingand recognizing the information included in the lead-in block indicatingthe range of block addresses recorded on a respective one of therecording surfaces of the disk, the information included in the lead-inblock indicating the configuration of the data frame, and the flagincluded in the lead-in block identifying the method for reproducing thedata frame, means for detecting the block address of a reproduced datablock, means for calculating a block address at which the reproductionends in accordance with a command from the host computer, and means forgenerating a command which controls the access to the disk andreproduction of a signal from the disk in accordance with theinformation obtained by the detection and recognition of the flag, thedetected block address, and the result of the calculation.

According to such a structure, since consecutive block addresses areallocated to the respective data blocks recorded on all of the recordingsurfaces of the disk, all of the recording surfaces of the disk can beaccessed and reproduced at high speed by using the conventionalinterface.

Other objects, features, and advantages of the invention will becomeapparent from the following detailed description of an embodiment of theinvention taken in conjunction with the accompanying drawings.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 shows the structure of one embodiment of a disk reproducingapparatus according to the present invention;

FIG. 2 illustrates the structure of a data frame used in the embodimentof FIG. 1;

FIG. 3 illustrates the structure of a lead-in block 205 of FIG. 2;

FIG. 4 illustrates the structure of a disk identification flag 210 ofFIG. 3; and

FIG. 5 is a flow chart indicative of an algorithm for signal processingin the embodiment of FIG. 1.

DESCRIPTION OF THE PREFERRED EMBODIMENT

A preferred embodiment of the present invention will be described withreference to the drawings.

FIG. 1 shows the structure of one embodiment of a disk reproducingapparatus according to the present invention as a block diagram.Reference numeral 1 denotes an optical disk having multilayeredrecording surfaces (recording surfaces on two or more layers); 2, a diskmotor; 3, a constant linear velocity (CLV) motor controller; 4, anoptical pickup which is capable of changing its focus to access aspecified one of the multilayered recording surfaces; 5, a preamplifier;6, a pickup movement controller; 7, a focus controller; 8, a digitalsignal processor; 9, an interface; 10, an interface bus; 11, a hostcomputer; 12, a system controller; 13, a disk informationdetection/recognition unit; 14, a block address detector; 15, a transferend block address calculation unit; and 16, an access/reproductioncontroller. The functions of the elements 15 and 16 may be implementedby reading programs stored in a medium such as a ROM or a floppy diskand executing the programs with a processor.

In FIG. 1, the optical disk 1 contains digital signals recorded on thefirst and second recording surfaces of the disk readable from one sideof the disk to be transferred to the host computer 11. The disk 1 isrotated at a constant linear velocity by the disk motor 2 controlled bythe CLV motor controller 3 so that a digital signal is reproduced by theoptical pickup 4 from the disk 1. At this time, tracking control of theoptical pickup 4 is provided by the pickup movement controller 6 andfocus control of the optical pickup 4 is provided by the focuscontroller 7 when one of the first and second recording surfaces isselected and accessed.

The structure of the optical disk 1 and the digital signal to berecorded will be described next with reference to FIGS. 2-4.

As shown in FIG. 2, one data block corresponding to a sector as aminimum unit which is recorded on the disk 1 is composed of a syncsignal 201 indicative of the boundary between two data blocks, arecording area identification flag 202 which identifies an area on thedisk in which the data block is to be recorded, a block address 203indicative of the address of the data block on the disk, and data 204.

As described above, the disk has first and second recording surfacesreadable from one side of the disk. N data blocks are arranged in orderof recording on the disk and consecutive addresses 1 to n are stored atcorresponding addresses 203 of the data blocks. A lead-in block 205having a structure shown in FIG. 3 is provided at the head of thearrangement of the data blocks to thereby compose a data frame 207.

The lead-in block 205 is indicative of the constitution information ofthe data frame 207 and has a format similar to that of the data blocks.Disk information 206 is stored in a data area, and includes a diskidentification flag 210 having a structure of FIG. 4 stored as part ofthe disk information 206. A frame head address 0 is stored at a blockaddress 203.

When consecutive data frames 207 thus produced are recorded on the disk1, the lead-in block at block address 0 and the data blocks at blockaddresses 1 to m (which is a natural number smaller than n) are recordedoutward from the innermost track on the first recording surface 208. Thedata blocks at block addresses (m+1) to n are recorded inward from theoutermost track on the second recording surface 209.

A flag "11" is stored as the disk identification flag 210, and a firstrecording surface end address 211 indicative of the address of a datablock recorded last on the first recording surface and a recorded blockcount 212 indicative of a data block count n recorded on the disk arerecorded as parts of the disk information 206.

A single optical disk is constituted which has the first and secondrecording surfaces superposed and recorded in the format mentionedabove.

Reproduction of digital data from the disk 1 will be described next withreference to the block diagram of FIG. 1 and the flow chart of FIG. 5.

In FIGS. 1 and 5, the innermost track on the first recording surface ofthe disk 1 is accessed with the optical pickup 4 before reproduction ofthe recorded data to reproduce the lead-in block 205 (step 501 of FIG.5), predetermined signal processing including detection of the syncsignal 201 and error correction is performed in the digital signalprocessor 8, and the disk information 206 is detected and recognized inthe disk information detection/recognition unit 13 (step 502). Thedetected disk information is delivered to the interface 9 which thendelivers the disk information to the host computer 11 via the interfacebus 10 in accordance with a predetermined protocol (step 503). The hostcomputer 11 sends an access command, a starting block address i at whichthe data blocks are to start to be accessed, and a transfer block countj to the interface 9 in dependence on the received disk information andin accordance with a predetermined protocol (step 504).

When the interface 9 receives a command from the host computer 11, theaccess/reproduction controller 16 controls the access and reproductionin accordance with the disk identification flag 210 of the diskinformation 206 detected previously.

If the detected disk identification flag 210 is other than the flag "11"indicative of a recording format to be dealt with in the presentinvention (step 505), the access/reproduction controller 16 delivers tothe system controller 12 a control command to reproduce j data blocks ofconsecutive addresses starting from the starting block address i on thedisk. The system controller 12 then controls the CLV motor controller 3and the pickup movement controller 6 to perform access/reproduction(steps 513 and 514). The reproduced data is then sent to the hostcomputer 11 via the digital signal processor 8, the interface 9, and theinterface bus 10.

If the detected disk identification flag 210 is "11", it is determinedthat the disk has been recorded using the method of FIG. 2. At step 506,the starting block address i is compared in magnitude with the outermosttrack block address m of the first recording surface obtained bydetection of the first recording surface end address 211 of the diskinformation 206 to select a recording surface at which the access is tobe started. If i is greater than m, the block address at which theaccess is to be started is present on the second recording surface.Thus, the focus of the optical pickup 4 is changed (step 507), and jdata blocks of consecutive addresses starting from the starting blockaddress i on the second recording surface are accessed and reproduced(steps 513 and 514). In order to change the focus, the conventionaltechnique disclosed, for example, in Nikkei Byte, September 1995, pp.129-130, FIG. 2, may be used.

If i is not larger than m, the starting block address i exists on thefirst recording surface. Thus, the transfer end block addresscalculation unit 15 calculates the transfer end block address (i+j)where the reproduction is to end on the basis of the starting blockaddress i and the transfer block count j. The result of the calculation(i+j) is compared with the recorded block count n obtained by detectionof the recorded block count 212 of the disk information 206 in theaccess/reproduction controller 16. If (i+j) is greater than n, thereproduction ends midway and the inability to reproduce the digitalsignal is reported via the interface 9 to the host computer 11.

The result of the calculation is compared with the outermost track blockaddress m on the first recording surface at step 508. If (i+j) is notgreater than m, it is determined that all of the data blocks to bereproduced are on the first recording surface. Thus, j data blocks ofconsecutive addresses starting from the starting block address i on thefirst recording surface are accessed and reproduced (steps 513 and 514).

If (i+j) is greater than m, it is determined that the data blocks to bereproduced exist in succession over the first and second recordingsurfaces. In this case, the data blocks are first started to be accessedat the starting block address i on the first recording surface andcontinue to be reproduced until a block address m is detected by theblock address detector 14 (steps 509, 510). When the block address m isdetected, the focus of the optical pickup 4 is changed to access thesecond recording surface (step 511) and a data block at a block address(m+1) existing on the outermost track of the second recording surface isreproduced to detect the block address (m+1) (step 512). Access to andreproduction of data blocks starting at the block address (m+1) is thenperformed (step 513) until the data block at the transfer end blockaddress (i+j) is reproduced (step 514). The block 500 including thesteps 505-513 fulfills the functions of the elements 15 and 16 ofFIG. 1. Programs corresponding to the respective steps in the block 500are stored in a recording medium as mentioned above.

As described above, in the present embodiment, when a digital signal isrecorded on a disk which has the first and second recording surfacesreadable from one side thereof, n data blocks recordable throughout allof the recording surfaces of the disk are arranged in order ofrecording, and a lead-in block containing disk information is providedat the head of the arrangement of the n data blocks to thereby compose adata frame. The lead-in block and the data blocks of block addresses 1to m are recorded outward from the innermost track on the firstrecording surface and the data blocks of block addresses (m+1) to n arerecorded inward from the outermost track on the second recordingsurface. Thus, since the consecutive block addresses are assignedthroughout all of the recording surfaces of the disk, all of therecording surfaces of the disk can be accessed and reproduced whileemploying the conventional interface.

The reproducing apparatus detects disk information recorded in thelead-in block and controls the system controller in accordance with thedetected disk information to thereby access and reproduce information inthe disk recorded in the present embodiment.

When the data blocks are reproduced continuously throughout the firstand second recording surfaces in the recording method of thisembodiment, the amount of movement of the pickup is minimized to therebyachieve high-speed access to the second recording surface.

While in the present embodiment the disk which has the first and secondrecording surfaces readable from one side thereof has been illustrated,the present invention is not limited to this particular case. Forexample, the present invention is applicable to disks which have threeor four surfaces readable from one side thereof. In this case, when, forexample, the data blocks to be recorded continue from the secondrecording surface to the third recording surface, the data blocks areassigned outward from the innermost track on the third recording surfacefor recording or reproducing purposes.

The structure and storage position of the disk identification flag 210and the storage positions of the first recording surface end address 211and the recorded block count 212 included in the disk information 206are not limited to the particular disclosed embodiment, but may bemodified depending on the various disk types.

The recording directions of the data frame on the first and secondrecording surfaces are not limited to those illustrated in theembodiment. The arrangement to be employed is required to minimize theamount of movement of the pickup between the recording surfaces. Forexample, consecutive data blocks may be recorded inward from theoutermost track on the first recording surface and then recorded outwardfrom the innermost track on the second recording surface.

What is claimed is:
 1. A method of recording digital signals on a disk,the disk having at least a first recording surface and a second recording surface, the digital signals being in the form of a data frame, the data frame including at least a lead-in block and n data blocks (n is a natural number), the lead-in block having a same format as the n data blocks, the method comprising the steps of: assigning n block addresses to respective ones of the n data blocks; assigning, to each of the n data blocks, information identifying an area on the disk in which a respective one of the n data blocks is to be recorded; recording m data blocks (m is a natural number, 0<m<n) of the n data blocks on the first recording surface of the disk; recording remaining (n-m) data blocks of the n data blocks on the second recording surface of the disk; and recording the lead-in block at the head of the data frame, the lead-in block includinginformation identifying an area on the disk in which the lead-in block is to be recorded, information identifying a number of recording surfaces, information identifying the block address of one of the m data blocks recorded last on the first recording surface, and information identifying the block address of a last one of the n data blocks in the data frame.
 2. A method according to claim 1, wherein the m data blocks are recorded on the first recording surface of the disk in a first radial direction of the disk; andwherein the remaining (n-m) data blocks are recorded on the second recording surface of the disk in a second radial direction of the disk opposite to the first radial direction of the disk.
 3. A method according to claim 1, wherein the first recording surface and the second recording surface are both readable from a same side of the disk by a single optical pickup.
 4. A method according to claim 1, wherein the information identifying an area on the disk in which a respective one of the n data blocks is to be recorded includes information representing a recording surface of the disk.
 5. A method according to claim 1, wherein the information identifying an area on the disk in which a respective one of the n data blocks is to be recorded includes information representing a type of block. 